In recent years, for a hermetic compressor in a freezing refrigerating system or air-conditioning system such as a refrigerator or a showcase, there are required an improvement in efficiency, a reduction of noise and highly reliable techniques, and besides, it is also an important factor to inexpensively provide the compressor.
A conventional hermetic compressor is shown in U.S. Pat. No. 5,971,720.
The above conventional hermetic compressor will be described below with reference to drawings. FIG. 14 is a sectional view of the conventional hermetic compressor. FIG. 15 is an exploded perspective view of a suction muffler attached to a cylinder head of the conventional hermetic compressor.
In FIG. 14, reference numeral 1 denotes a hermetic vessel. Reference numeral 2 denotes a compressing element, which is accommodated in the hermetic vessel 1. Reference numeral 3 denotes an electric motor element, which is connected with the compressing element 2. Reference numeral 4 denotes a cylinder, which defines a compression chamber 5 of the compressing element 2. Reference numeral 6 denotes a piston, which reciprocates in the cylinder 4. Reference numeral 7 denotes a valve plate, which seals one end of the cylinder 4. Reference numeral 8 denotes a cylinder head, which fixes the valve plate 7 to the cylinder 4 and fixes a suction muffler (not illustrated in FIG. 13) to the valve plate 7. Reference numeral 10 denotes a suction pipe. Reference numeral 11 denotes freezer oil, which is collected in the bottom portion of the hermetic vessel 1.
In FIG. 15, reference numeral 12 denotes a suction muffler as silencing means for attenuating noise generated in the compression chamber 5 and a suction valve (not illustrated). In view of an improvement in performance of the hermetic compressor, it is desirably made of a material with a low thermal conductivity, e.g. a synthetic resin material. In consideration of the use environment of a coolant gas atmosphere and a high temperature, the synthetic resin material may be a material of PBT or PPS.
The suction muffler 12 is made up from a muffler main body 13 and a muffler cover 9. The muffler main body 13 and the muffler cover 9 are joined to each other by welding or fitting to define a muffler space 14. Reference numeral 15 denotes an inlet pipe, whose one end is open in the hermetic vessel 1 and other end is open to the muffler space 14. Reference numeral 16 denotes an outlet pipe, whose one end is open to the valve plate 7 side and other end is open to the muffler space 14.
The operation of the hermetic compressor constructed as above will be described below. Coolant gas that has returned from a freezing cycle (not illustrated) to the hermetic compressor is once released into the hermetic vessel 1 through the suction pipe 10. The coolant gas then passes through the suction muffler 12 and the valve plate 7 and flows in the compression chamber 5, where the coolant gas is compressed by the piston 6 that is reciprocating due to the rotation of the electric motor element 3, and then the coolant gas is sent to the freezing cycle.
At this time, a pressure pulsation of the coolant gas occurs in the compression chamber 5 due to the reciprocation of the piston 6 and the opening/closing operation of the suction valve. The pressure pulsation having occurred in the compression chamber 5 propagates in the reverse direction to the flow of the coolant gas, and is once released into the muffler space 14 through the outlet pipe 16. The pressure pulsation then attenuates by being released into the hermetic vessel 1 through the inlet pipe 15, and is radiated as low noise.
On the other hand, another conventional hermetic compressor is shown in U.S. Pat. No. 5,496,156. FIG. 16 is a sectional view of the other conventional hermetic compressor. In FIG. 16, reference numeral 18 denotes a hermetic vessel. Reference numeral 19 denotes a compressing element, which is accommodated in the hermetic vessel 18. Reference numeral 20 denotes an electric motor element, which is connected with the compressing element 19. Reference numeral 21 denotes a cylinder, which defines a compression chamber 22 of the compressing element 19. Reference numeral 23 denotes a piston, which reciprocates in the cylinder 21. Reference numeral 24 denotes a valve plate, which seals one end of the cylinder 21. Reference numeral 25 denotes a suction valve, which is interposed between the valve plate 24 and the cylinder 21. Reference numeral 26 denotes a cylinder head, which fixes the valve plate 24 to the cylinder 21 and fixes a suction muffler 27 to the valve plate 24. Reference numeral 28 denotes a suction pipe. Reference numeral 29 denotes freezer oil, which is collected in the bottom portion of the hermetic vessel 18. The suction muffler 27 is made up from a suction muffler main body 30 and a suction muffler cover 31. The suction muffler main body 30 and the suction muffler cover 31 are joined to each other by welding or fitting to define a muffler space 32. Reference numeral 33 denotes an inlet portion, which fluidly connects the hermetic vessel 18 and the muffler space 32 with each other. Reference numeral 34 denotes an outlet pipe, whose one end is open to the valve plate 24 side and other end is open to the muffler space 32.
The operation of the hermetic compressor constructed as above will be described below. Coolant gas that has returned from a freezing cycle (not illustrated) to the hermetic compressor is once released into the hermetic vessel 18. The coolant gas then passes through the suction muffler 27 and the valve plate 24 and flows in the compression chamber 22, where the coolant gas is compressed by the piston 23 that is reciprocating due to the rotation of the electric motor element 20, and then the coolant gas is sent to the freezing cycle.
At this time, a pressure pulsation having occurred in the compression chamber 22 propagates in the reverse direction to the flow of the coolant gas, and is once released into the muffler space 32 through the outlet pipe 34. The pressure pulsation then attenuates by being released into the hermetic vessel 18 through the inlet portion 33, and is radiated as low noise.
The above-described conventional construction, however, has a complicated shape because the muffler main body 13 and the muffler cover 9 form the respective side wall surfaces of the suction muffler 12. The complicated shape causes an increase in cost for manufacture. Besides, since the complicated shape further causes a large deformation upon molding, the insufficient connection between the muffler main body 13 and the muffler cover 9 brings about a leakage. Therefore, a sufficient silencing effect can not be obtained. The above conventional construction has these disadvantages.